/*
 * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <assert.h>
#include <io_driver.h>
#include <io_storage.h>
#include <semihosting.h>



/* Identify the device type as semihosting */
static io_type_t device_type_sh(void)
{
    return IO_TYPE_SEMIHOSTING;
}


/* Semi-hosting functions, device info and handle */

static int sh_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
static int sh_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
        io_entity_t *entity);
static int sh_file_seek(io_entity_t *entity, int mode, ssize_t offset);
static int sh_file_len(io_entity_t *entity, size_t *length);
static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
        size_t *length_read);
static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
        size_t length, size_t *length_written);
static int sh_file_close(io_entity_t *entity);

static const io_dev_connector_t sh_dev_connector = {
    .dev_open = sh_dev_open
};


static const io_dev_funcs_t sh_dev_funcs = {
    .type = device_type_sh,
    .open = sh_file_open,
    .seek = sh_file_seek,
    .size = sh_file_len,
    .read = sh_file_read,
    .write = sh_file_write,
    .close = sh_file_close,
    .dev_init = NULL,    /* NOP */
    .dev_close = NULL,    /* NOP */
};


/* No state associated with this device so structure can be const */
static const io_dev_info_t sh_dev_info = {
    .funcs = &sh_dev_funcs,
    .info = (uintptr_t)NULL
};


/* Open a connection to the semi-hosting device */
static int sh_dev_open(const uintptr_t dev_spec __unused,
        io_dev_info_t **dev_info)
{
    assert(dev_info != NULL);
    *dev_info = (io_dev_info_t *)&sh_dev_info; /* cast away const */
    return 0;
}


/* Open a file on the semi-hosting device */
static int sh_file_open(io_dev_info_t *dev_info __unused,
        const uintptr_t spec, io_entity_t *entity)
{
    int result = -ENOENT;
    long sh_result;
    const io_file_spec_t *file_spec = (const io_file_spec_t *)spec;

    assert(file_spec != NULL);
    assert(entity != NULL);

    sh_result = semihosting_file_open(file_spec->path, file_spec->mode);

    if (sh_result > 0) {
        entity->info = (uintptr_t)sh_result;
        result = 0;
    }
    return result;
}


/* Seek to a particular file offset on the semi-hosting device */
static int sh_file_seek(io_entity_t *entity, int mode, ssize_t offset)
{
    long file_handle, sh_result;

    assert(entity != NULL);

    file_handle = (long)entity->info;

    sh_result = semihosting_file_seek(file_handle, offset);

    return (sh_result == 0) ? 0 : -ENOENT;
}


/* Return the size of a file on the semi-hosting device */
static int sh_file_len(io_entity_t *entity, size_t *length)
{
    int result = -ENOENT;

    assert(entity != NULL);
    assert(length != NULL);

    long sh_handle = (long)entity->info;
    long sh_result = semihosting_file_length(sh_handle);

    if (sh_result >= 0) {
        result = 0;
        *length = (size_t)sh_result;
    }

    return result;
}


/* Read data from a file on the semi-hosting device */
static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
        size_t *length_read)
{
    int result = -ENOENT;
    long sh_result;
    size_t bytes = length;
    long file_handle;

    assert(entity != NULL);
    assert(buffer != (uintptr_t)NULL);
    assert(length_read != NULL);

    file_handle = (long)entity->info;

    sh_result = semihosting_file_read(file_handle, &bytes, buffer);

    if (sh_result >= 0) {
        *length_read = (bytes != length) ? bytes : length;
        result = 0;
    }

    return result;
}


/* Write data to a file on the semi-hosting device */
static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
        size_t length, size_t *length_written)
{
    long sh_result;
    long file_handle;
    size_t bytes = length;

    assert(entity != NULL);
    assert(buffer != (uintptr_t)NULL);
    assert(length_written != NULL);

    file_handle = (long)entity->info;

    sh_result = semihosting_file_write(file_handle, &bytes, buffer);

    *length_written = length - bytes;

    return (sh_result == 0) ? 0 : -ENOENT;
}


/* Close a file on the semi-hosting device */
static int sh_file_close(io_entity_t *entity)
{
    long sh_result;
    long file_handle;

    assert(entity != NULL);

    file_handle = (long)entity->info;

    sh_result = semihosting_file_close(file_handle);

    return (sh_result >= 0) ? 0 : -ENOENT;
}


/* Exported functions */

/* Register the semi-hosting driver with the IO abstraction */
int register_io_dev_sh(const io_dev_connector_t **dev_con)
{
    int result;
    assert(dev_con != NULL);

    result = io_register_device(&sh_dev_info);
    if (result == 0)
        *dev_con = &sh_dev_connector;

    return result;
}
